Down Mixer plug-in
You can use the Down Mixer plug-in to adjust the input format of the surround master channel strip. You can do this to quickly check the surround mix in stereo, for example.
Channel mapping, panning, and mixing are handled behind-the-scenes. You do, however, have some control over the mix:
Down Mixer parameters
Dest Format pop-up menu: Choose the surround destination format: To Quad, To LCRS, To Stereo.
Level sliders: Control the respective channel levels.
Note: The number, and names, of sliders depends on the chosen plug-in format.